Gastric Bypass May Curb Hunger Hormone

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Decline in Ghrelin After Gastric Bypass May Prompt Rapid Weight Loss

July 12, 2004 -- A sudden drop in a hormone that stimulates
appetite may be at least partially responsible for the rapid weight loss seen
in obese persons who undergo gastric bypass surgery, a new study suggests.

Researchers found that levels of the hunger hormone known as
ghrelin declined significantly following gastric bypass surgery. Gastric bypass
is a common form of weight loss surgery in which the stomach is made smaller by
creating a small pouch. The pouch is attached to the middle portion of the
small intestine, bypassing the rest of the stomach and the upper portion of the
intestine.

Ghrelin is a hormone produced in the stomach that triggers
appetite and is thought to play an important role in regulating body weight.
Levels of ghrelin typically rise before meals and quickly decline after
eating.

"This study demonstrates that complete division of the
stomach, forming a small vertical pouch, contributes to the decline in
circulating ghrelin levels," write researcher Edward Lin, DO, of the Emory
University School of Medicine, and colleagues. "This may explain, in part,
the loss of hunger sensation and rapid weight loss observed following gastric
bypass surgery."

Weight Loss Surgery Stalls Hunger Signals

In the study, published in the July issue of the Archives of
Surgery, researchers measured ghrelin levels in 42 morbidly obese persons
before and after surgery. Thirty-four of the participants underwent a gastric
bypass and eight had other forms of procedures involving the stomach. Six
non-obese persons undergoing anti-reflux surgery also served as a comparison
group.

The study showed that levels of ghrelin were much lower in
obese persons following gastric bypass surgery. Before surgery, ghrelin levels
were 355 picograms per milliliter among those who had a gastric bypass compared
with 246 picograms per milliliter following the procedure.

No significant changes were found in ghrelin levels among obese
persons who had other gastric procedures or in the non-obese comparison
group.

Researchers say they believe this is the first study in humans
to show a decline in ghrelin following gastric bypass surgery.

They say the results suggest that weight loss surgeries that do
not involve reducing or dividing the stomach tissue may not adequately lower
ghrelin levels, reduce hunger, and induce weight loss.